Dee. is. i»i6 Influence of Bordeaux Mixture on Transpiration 
543 
Tabi^S V .—Effect of Bordeaux mixture , copper sulphate , and barium sulphate on the 
rate of transpiration of potted soy-bean plants 
[Period before treatment, Feb. 29 to Mar. 4: period after treatment, Mar. 4 to Mar. xx, 1916I 
Transpiration quantities. 
Plant No. 
Period before treatment. 
Series 
A 
(Bor¬ 
deaux 
mix¬ 
ture). 
Series 
B 
(ba¬ 
rium 
sul¬ 
phate). 
Series 
C 
(copper 
sul¬ 
phate). 
Series 
D 
(con¬ 
trol). 
Period after treatment. 
Series 
A' 
(Bor¬ 
deaux 
mix¬ 
ture). 
Series 
B' 
(ba¬ 
rium 
sul¬ 
phate). 
Series 
a 
(copper 
sul¬ 
phate). 
Series 
D 
(con¬ 
trol). 
o» 
177.9 
130. s 
76.4 
142.3 
94.8 
8s -7 
Average. 
Transpiration ratio, 
Difference. 
W) 
34*2 
64. o 
77* S 
65.8 
67.9 
55-6 
<B> 
53-0 
34-0 
45*8 
38.7 
46.5 
37- S 
(C) 
49.0 
56.6 
39*4 
33*5 
82. o 
92.3 
( D ) 
53-1 
58. 2 
33-5 
65-3 
46.6 
43*9 
<ri') 
128.1 
254-7 
304. 8 
217.8 
265.1 
227. 8 
(B f ) 
131-3 
77-4 
103.5 
88. 7 
135-6 
87. 7 
(C') 
•195- 6 
198.6 
124.9 
75*6 
252.0 
253* 2 
60.8 
42- 5 
58. 8 
50.1 
233-0 
104. o 
183.3 
117-8 
ft 
B D= 
0.85 
C D=* 
x.17 
fA # D=* 
l 1.98 
B' D= 
0.88 
a d= 
1.55 
o. 77+ 
0.034- 
o. 384- 
Prom the data of Table V it appears that of the three kinds of mate¬ 
rials applied to the leaves of soy-bean plants Bordeaux mixture is the 
most effective in bringing about * an increased rate of water loss. The 
plants sprayed with Bordeaux mixture here showed, relative to the 
control plants, an average rate of water loss 63 per cent higher than 
the average rates of the same plants before spraying. The leaves of the 
plants dusted with copper sulphate showed a corresponding increase of 
37 per cent, while the plants sprayed with barium sulphate show an 
increase in the average rate of water loss, relative to the control plants, 
of only 3 per cent over the average rate for the standardization period. 
The results here obtained are in entire accord with the conclusions 
reached by Duggar and Cooley (6) that certain specific characters of the 
films are important factors, considered in relation to the modified rates 
of transpiration. The further suggestion of these authors that modified 
leaf temperature induced by heat absorption due to the color of the sur¬ 
face films is an important factor might also be considered as effective 
in bringing about the results obtained here, since a film of Bordeaux 
mixture, being darker in color than either of the two other surface cov¬ 
erings used may be assumed, without any other direct evidence, to have 
a higher heat-absorbing power than either copper sulphate or barium 
sulphate. It is scarcely probable, however, that modified leaf tem¬ 
peratures, induced by differences in the heat-absorbing powers of the 
surface films here used, could account for any great portion of the differ¬ 
ences in the rates of water loss observed. 
